Passive Ability: Soul Snatch - Each hit drains 1 HP and 1 MP, increasing by one per level, capping at 18 HP and MP at Lv18.

Q: Unholy Strafe - MP cost: 70/90/110/130/150

For 3 attacks, increase attack speed to 2.500 and critical chance by 15%. For each level of the skill, the crit chance is increased by 10% (up to 55% at max level).

Cooldown: 10 Seconds.

W: Cursed Bullets - MP cost: 50/60/70/80/90

Loads your musket with cursed bullets. Enemies hit with your normal attacks will be cursed and have their critical chance and attack speed lowered for a short time. For each level of the skill, the critical chance reduction is 5% and the attack speed reduction is 5% (up to 30% critical chance/30% attack speed reduction at max level). Lasts 5 seconds.

Cooldown: 28 Seconds.

E: Grenade of Despair - MP cost: 80/90/100/110/120

Throws forth a grenade that damages and sets your enemies on fear. The damage formula is 25% of your total AD and the fear duration increases by 0.5 each time you level the skill, starting with 1 second (maximum 3 seconds). Only the target in the center of the explosion will be feared, the enemies around will only be damaged. (much like Heimer's grenade).

Cooldown: 20 Seconds

R (Ultimate): Akimbo of The Dead - MP cost: 150/200/250

Grim's endless desire for revenge empower his arms, allowing him to wield a secondary musket, doubling his attack damage, but lowering his attack speed by 30%. Also applies a minor burn effect to regular attacks (30 magic damage per second, lasts 5 seconds).

I haven't any character design yet, i only have in mind he'd be skull headed and use a long, black, ripped cape that goes till the ground, and wear a black hat like Alucard's (but black). Also a few golden rings. Also also, he floats, so no legs.

Just personal opinion here.
With his AD being doubled with his ult, imagine getting only 200 AD from items, ulting, then using W and landing a crit with IE. That's 1,000 damage. Three times, very quickly. Thought Darius ult QQ's were bad? Also,
W seems overpowered. The AS and crit drain seem WAY to harsh.

Just personal opinion here.
With his AD being doubled with his ult, imagine getting only 200 AD from items, ulting, then using W and landing a crit with IE. That's 1,000 damage. Three times, very quickly. Thought Darius ult QQ's were bad? Also,
W seems overpowered. The AS and crit drain seem WAY to harsh.

As for the W: I believe increasing the cooldown would deal with the problem.

As for his ult, it has a huge CD and lasts very little. CC/disable/exhaust him, and he should be done with.

Anyway, toned down the W a little. Keep in mind that it's extremely useless at low levels, or if used against a mage.

His ult is really well thought out, but doubling his AD for damage, is a little OP, because think of Vayne's ult it's a similar buff but not anywhere near double. He would be hitting like a truck, plus crits... it's just every Teemo's nightmare. other than that, some great material here, I hope it gets noticed!

Passive - They removed the mana drain from one of the on-hit abilities for a reason. A few auto attacks meant that the tank was oom for the fight and cannot do anything. Draining it and giving it back to yourself means you could make all your abilities cost 25% of your mana at every level and you can just get it back in a minute.

W - More dueling power, now can anyone who dives you not deal damage with auto attacks because they are slow, but if you get a shot off on the AD carry then they are basically out of the fight. 30% is huge for both AS and crit chance.

E - A fiddle fear in a can. Land it and the enemy does not even attack you for 3 seconds. That is way too long and means you can get to max range and kill. You are undivable by assassins or bruisers.

R - IE means gg when you get double AD. So what if you get lower attack speed if you can just put on Q and be at ~1.8 AS. That is the usual AS you get with PD and zerkers.

Every ability except his grenade is just a steroid or passive ability, making him an auto attack only champion. No abilities involved. Way too strong of a champion it is not even funny with stuff that Riot is trying to avoid.